Average state wheat yields for most of the Southeast typically top 40 bushels per acre, with many producers regularly pushing 70 to 80 bushels.
Southwest wheat yields are lower.
“Some of the difference is due to environment,” says Steve Phillips, International Plant Nutrition Institute. “Annual rainfall is greater in the Southeast, but rainfall distribution is more important than the total.”
He says moisture during peak need may not be significantly different in parts of Oklahoma than in the Southeast.
“Management is the big difference (in average yield disparity),” Phillips said during an intensive wheat management presentation at the recent No-till Oklahoma Conference in Norman. “If managed properly wheat is a money maker,” he said. “Focus on yield potential.”
Phillips said stand establishment is a crucial first step. That can be challenging with no-till wheat, especially when planting behind a high volume residue crop. “Trying to plant no-till wheat into 200-bushel corn residue can be tough,” he said.
Setting the planter up properly makes a difference. Planting depth, stalk control, drill calibration and properly set row cleaners are essential.
He said precision ag technology also helps with planting efficiency. GPS guidance system adoption, he said, has steadily increased over the past decade. “We’ve seen a 10-fold increase in dealer offerings for GPS the last 10 years. Now, some 40 percent of Southeast dealers will add automated section control this year for spraying and planting.”
Automated section control, Phillips said, eliminates skips and “significantly limits overlaps.”
Technology accounts for significant savings, he said. GPS saves 10 percent; variable rate application saves 7 percent; and automated section control saves 5 percent. “That’s a total savings of 22 percent,” Phillips said.
Fertility is a key area for intensively managed wheat. “Proper soil pH is a prerequisite for a proper fertility program and I have never encountered a group that cared less about pH than Oklahoma farmers,” said Phillips, an Oklahoma native.
“But as farmers develop a more intensive management system for wheat, attention to pH becomes more critical,” he said.
Rotation crops also may affect pH. He said phosphorus, potassium and secondary nutrients also may be affected by rotation and a more intense management system.
But nitrogen management is the most difficult and the most intensively managed nutrient.
Phillips said nitrogen management includes four critical factors — source, rate, timing and placement. If either of those factors is off, the efficacy of application may be adversely affected. “Think about it holistically,” he said.
He said many farmers adhere to established routines in nutrient management. “It’s tradition, the way we’ve always done things,” he said. “But we can and should think about manipulating fertilization programs.”
Phillips said most of his recent work has been for Southeastern conditions. “But fertility rate decision principles are universal.” He said precise rates from a Southeastern state might not work for Oklahoma, but the principle by which that rate is established will be just as effective in one state as another.
He said nitrogen source is often a matter of what’s cheapest or what’s available. “But we need to think about supplying the plant a nitrogen source in available form and recognize any synergism among elements. The best value depends on being more selective,” Phillips said.
He said “enhanced efficiency products” may have a place in intensive wheat production but producers must know what each product is intended to do. “There are no silver bullets,” he said. “Each of these products does something different and often work in specific conditions. They work in the environment they were designed to work in.”
He said the best nitrogen source will be available to the plant. “Also, recognize the existing loss pathways (leaching, volatilization, etc.).”
Rate depends on yield goal. “For 40 bushel wheat, you need 74 pounds of nitrogen per acre,” Phillips said. “Soil test regularly — every two to three years and annually when justified by research. And apply recommended rates.”
He said farmers using grid sampling should sample “every three years or so after establishing management zones. Follow that with yield mapping and adjust or re-sample if conditions change.”
Phillips said producers should set realistic yield goals and fertilize accordingly. “Set a goal somewhere between average and maximum potential,” he said. “At least get in the ballpark. Yield monitoring will help.”
In-season tissue testing can improve fertility management. Phillips recommends tissue tests at growth stage 30. “Walk the fields and collect good samples.”
Crop sensors also provide in-season help for analyzing fertility needs. Philips said a sensor, such as the Green Seeker, can help improve nitrogen use efficiency. “The Green Seeker has a lot of uses including identifying weed pressure, mapping, applying plant growth regulators and defoliants for cotton.”
He also cautioned wheat producers to take care with “early season nitrogen applications. You can increase the risk of lodging, disease and damage from a late freeze. We have a very high risk of freeze damage this year. Scout fields and apply appropriate rates.”
Timing fertilizer applications should coincide with “when the crop will take it up the best. And uptake is not linear,” Phillips said. “In Kentucky, wheat needs little nitrogen from February through March. Application from late March through early April is usually better but growers can’t always go by the calendar in intensively managed wheat.”
Phillips said if the fertility rate is wrong, timing will not make much difference.
“In the Southeast, two to three split applications in the spring show significant yield advantages. Proper fertilizer timing is when the crop requirements indicate a need. Also, make certain to recognize the existing loss pathways for nitrogen.”
Fertilizer placement depends on soil dynamics and the mobility of the nutrient. “Nitrogen will move,” Phillips said. “Phosphorus and potassium are mostly taken up at the soil surface. A highly immobile nutrient such as phosphorus concentrated just below the soil surface will increase plant root activity.”
Banding may be an efficient application method.
He said nutrient mobility may account for field spatial variability. “Also, when we fertilize for the average, we rarely get it right.”
Phillips said wheat farmers interested in increasing productivity with more intensive management should incorporate “principles that drive actions away from tradition and to a scientific method of production.”